DETERMINATION OF PREG-ROBBING IN GOLD ORES OF THE NORTHWEST OF THE PROVINCE OF SAN JUAN, ARGENTINA.

Abstract

The objective of this work was to determine the presence of preg-robbing in a blend of sulphide samples from the Gualcamayo región. The gold grade in this blend was 0,84 g/t and the organic coal grade was 0,34 %. The potential preg-robbing (PRP) was determined using a known method, performing agitation leaching tests with cyanide solutions of different initial gold concentrations. Then, leaching tests were performed by agitation in flasks without activated coal (BRT) and with activated coal (CIL). Finally, column leaching/adsorption test was completed using 65 kg of crushed sample 90 %-1”. The PRP determination method showed results similar to the BRT and CIL. The PRP was 16,7%. Actual  gold extraction in the PRP was 42,9% and in the BRT was 39,5%. The gold inferred extraction in the PRP was 51,5% and the gold extraction in the CIL 53,6%. The difference of gold extraction between the BRT and in CIL confirmed the preg-robbing in the BRT. In this test, the adsorbed gold was 0,12 g/t of ore. The gold extraction in column leaching test was 43,4% and adsorbed gold was 0,07 g/t of ore. The extraction of gold obtained in the BRT was slightly lower than that obtained in the column, due to preg-robbing more pronounced in BRT, produced probably by an increased release of organic carbon (or other adsorbent species) in the grinding.